Dry concentrator



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Sept E3, Mw .1. Ross DRY coNoENTRAToR 2 Sheets-Sheet l Filed April 8, 1937 DRY GONCENTRATOR Filed April 8, 1957 .2 sheets-sneak Za Syvum/JM qan f H 055 Patented Sept. 13, 1938 UNITED STATES PATENT GFFIQE DRY CONCENTRATOR John Ross, Custer, S. Dak.

Application April 8, 1937, Serial No. 135,775

3 Claims.

This invention relates to concentrators and particularly to a dry concentrator for concentrating gold sands.

The general object of the invention is to pro- 5 vide a concentrator of a Very simple construction including a concentrating tubular element through which the gold containing the sand is blown, the bottom of the concentrator being provided with riffles so that the heavier materials will fall to the bottom of the concentrating tube while the lighter` materials, such as sand and gravel will be blown out of the concentrator tube at the end thereof.

Another object is to provide means whereby the material being concentrated may be heated before being discharged into the concentrating tube, and another object is to provide means for regulating the flow of materials to the concentrating tube.

A further object is to provide means whereby the concentrate may be readily removed from the concentrating tube when necessary.

Other objects will appear in the course of the following description.

My invention is illustrated in the accompanying drawings wherein:-

Figure l is a side elevation of a dry concentrator constructed in accordance with my invention.

Figure 2 is an enlarged section on the line 2 2 of Figure 1.

Figure 3 is an enlarged vertical section through the feeding mechanism and a portion of the concentrating tube.

Referring to these drawings, I designates a concentrating tubular member which may have any desired diameter and which is supported adjacent its forward and rear ends or at any suitable points by supporting brackets II. The 40 tube is embraced by a band I2 extending from one supporting bracket, the band being split and held clamped upon the tube by the bolt I3. Preferably the forward end of the tube IIJ is screw-threaded for the attachment, if desired, of a pipe coupling I4. The rear end of the tube I0 is operatively connected to a fan or blower casing l5 of any suitable or usual construction having therein the fan I6 which is illustrated as being driven by a belt or sprocket Il from a 50 motor I8, preferably an internal combustion motor.

The tube I D is formed in two sections connected by a four-way pipe fitting I9. The downwardly discharging branch of this pipe fitting is closed by a removable plug 20. Inserted in the upwardly extending branch of this pipe fitting I9 is a pipe reducing bushing 2l. Extending downward through this bushing and vertically adjustable therein is a feed tube 22, the upper end of which terminates n a hopper 23.

Disposed at any desired distance above the pipe IB is a hopper or bin 24 having a discharge pipe 25 discharging into the hopper 23 and provided with a shut-off gate 26. Surrounding the feed tube 22 is a sleeve 2'I which may be connected by a pipe 28 to the exhaust from the motor I8 so that the heated products of combustion from this motor may be discharged into this sleeve 2l and surround that portion of the feed pipe 22 just above the bushing 2|.

Disposed at intervals along the bottom of the tube l0 are the forwardly and upwardly inclined riffles 29, each riffle being approximately semicircular in form, as illustrated. As illustrated. the tube I il is formed with a plurality of diagonal kerfs 30 into which the rifes 29 are inserted. These riilles are preferably one-third as high as the inside diameter of the tube and slant toward the discharge end of the tube.

While I do not wish to be limited to this, yet preferably hard rubber riffles are used as these will wear longer than steel riiiles. When, however, the sand or gravel is moist, the steel riflies work the best as the material slides over them easier. These riiiies are spaced from 4 to 6 apart, according to the size of the tube.

The rifes are inserted in the kerfs 3B and after the rife is put in place, the walls of the kerf are slightly battered with a hammer so that they overhang the riiiie slightly and this will prevent the rilile from falling out while the shoulders or corners 3I prevent the riflies from slipping sidewise.

The feed tube 22 is one-third as large in diameter as the concentrating tube I0. The blast of air must be strong enough to keep sand and gravel moving and this, of course, is regulated either by proper valves or by controlling the engine speed. The forward end of the tube I0 is supported slightly higher than the feed end of the tube I0 and I find that l" to the foot gives the proper angle. This permits the washing out of the concentrating tube when the concentrating operation is finished.

To clean out the concentrating tube, the gate 26 is first closed and the blower is run until the feed tube and feed hopper are entirely empty. Then the bolt I3 of the clamp I2 is loosened. This permits the forward section of the concentrating tube to be rotated within the fitting I9 and given a one-half turn. The riiiies are then at the top of the concentrating tube and by tapping the tube with a hammer, all the concentrates will drop to the bottom of the tube or onto the smooth side of the inverted tube. 'Ihen a suitable receptacle is placed beneath the plug 20 and the plug removed. By pouring a pail or two of water into the discharge end of the tube Il), the water will ow rearward and wash all the concentrates back an-d they will come out through the lower opening of the four-Way pipe fitting and be discharged into the receptacle. The plug 20 should be left out until all the water has drained out of the tube before starting up again.

By screwing the feed tube 22 up or down through the reducing bushing 2l, the feed may be regulated. By screwing the feed tube up, the feed will be increased and will be decreased by screwing the feed tube down. Of course, where the gravel is damp, the feed must be slowed up somewhat and while the moisture does not interfere with proper separation, yet I have made provision to apply a little heat around the feed tube, as before described, without any additional cost to the operator.

It is to be noted that the feed pipe 25 extends straight downward from the bin or hopper 24 and that the pipe 22 also extends straight downward. This is necessary Where this concentrator is being used for placer sands and gravel because such sand or gravel is very likely to be damp. This dampness does not occur where ore has to be ground up for concentration, but it does occur where this concentrator is used, as it is particularly designed to be used for placer mining. If the feed tube or any other feeding member were inclined even at a steep angle, there is liability of the sands, because of their moisture, sticking to the inclined surface and clogging. This is not the case, however, where the feed tube is vertical. Furthermore, I have provided a heating means, namely, the spaced sleeve 21, for driving olf any latent moisture which may still remain in the sand.

It is also an absolute necessity in an apparatus of this kind that the feed should be capable of being regulated and this is secured by the adjustment of the feed tube 22 nearer to or further from the bottom of the concentrating pipe. If the feeding means is not capable of adjustment, then the machine will either be overloaded or run empty. The tube 22 will feed the sand down into the concentrating tube no faster than the blower carries the sand away. Furthermore, with this construction, should the blower stop from some cause, the sand will stop feeding into the tube, in other words, it will build up beneath the lower end of the tube and as it cannot pass laterally from the tube, it will stop all feed from the tube.

By placing the blower l5 at the rear end of the concentrating tube lll and placing the feed in front of the blower, I prevent the blower from being scored or injured by the ne particles of sand which would be the case were a suction fan used for drawing the sand and gravel through the concentrating tube. Furthermore, a suction fan has much less power than a blower. It will be noted that the tube lll forward of the feed tube 22 is unobstructed except by the relatively shallow riffles in the bottom of the tube. Thus there is nothing which will impede the free movement of 'the sand and gravel and lighter material along the tube, and there is nothing which will tend to disturb the gold or heavier material which has fallen into the spaces between the riiiles.

This concentrator can be built in different sizes, from a hand-operated machine up to a size that will handle a large amount of sand and gravel. I have found that it will work in connection with any kind of gravel screening plant.

The gravel that travels through the concentrator must be screened through a mesh screen so that the blower can properly handle it. Of course, it is to be understood that the screened gravel is discharged into the bin or hopper 24 and from there it passes through the feed spout into the feed tube hopper and thence into the feed tube and into the concentrator. There the blower blows it through the concentrating tube and over the riles. Inasmuch as the gold is much heavier than the sand and gravel, it will settle to the bottom of the concentrating tube while the sand and gravel will be blown out. As before stated, the discharge end of the concentrating tube IS is provided with a coupling I4 s0 that the concentrating tube may be extended, if necessary, by connecting another piece of tubing having, of course, the riflies 29 therein.

Where there is a good deal of fine or flour gold in the sand and gravel together with coarse gold or nuggets larger than or larger than the reticulations of the screen, it is advisable to use a larger screen and use two concentrators on one machine side by side of the same size and design. Then the undersized material which has passed through the screen is again screened and this ne material is run through one concentrator and the coarser material through the other. rline blast of air that acts upon the ne material must be reduced in strength while the blast of air that carries away the coarser material may be increased. By doing this, all the ne and all the coarse gold can be saved. Obviously where a gang of these machines are being used, all the blowers may be operated from one shaft driven by one motor.

What is claimed isi- 1. A dry concentrator of the character described, including a four-way pipe fitting, a tubular concentrator section rotatably engaged with the forward end of the pipe fitting and having a series of riffles on its bottom, a second pipe section connected to the rear end of the pipe fitting, a blower communicating with the last named pipe section, a cleanout plug vdisposed at the lower end of the pipe section, a pipe reducing bushing in the upper end of the four-way pipe section, a feed tube extending through the bushing and vertically adjustable therein, and means for regulatably discharging sand and gravel into said hopper.

2. A dry concentrator of the character described, including a concentrating tube having a series of forwardly inclined bales disposed at spaced distances in the bottom of the tube, means for rotatably supporting the tube whereby it may be turned through a half-circle, a blower discharging into the rear end of the tube, a feed pipe discharging into the rear end of the tube, and a cleanout opening at the rear end of the tube, the concentrating tube being upwardly inclined towards its forward end whereby when the concentrating tube is inverted and the cleanout opening is opened, the concentrate will fall to the bottom of the concentrating tube and may be washed out of the cleanout opening.

3. In a dry concentrator of the character described, a concentrating tube, the bottom of the tube having a series of kerfs cut therein and slanting toward the forward end of the tube, and baflies inserted and held in place in said kerfs.

JOHN ROSS. 

